Charged particle tomography techniques, such as those that rely on cosmic ray muons, generate three-dimensional images of volumes using information contained in the Coulomb scattering of the particles. Since muons are capable of deeper penetration into the object than X-rays, muon tomography can penetrate larger radiation lengths of materials to produce images through much thicker material (e.g., with larger radiation lengths) than X-ray tomography (e.g., CT scans). Applications of tomography techniques include detection of nuclear material in, for example, road transport vehicles and cargo containers, characterization of nuclear waste, monitoring of potential underground sites used for carbon sequestration, prediction of volcanic eruptions, medical imaging and other imaging and detection applications.
Tomography techniques most commonly rely on either transmission radiography or scattering tomography. With scattering tomography, both incoming and outgoing trajectories for each particle are reconstructed by measuring the deviation in trajectory of the charged particle (e.g., muons and electrons), as measured by position detectors, through the tomographic volume. However, knowledge of the particle's momentum can improve the material density estimates that are obtained from reconstruction.